The present invention relates to a process for production of solid sorbitol.
In general, sorbitol can be produced by the hydrogenation of glucose which can be obtained by the hydrolysis of starch. As the sorbitol obtained by such a process contains much amount of water, it is concentrated to about 70% by weight of solid or further dried to powder for commercial use. The concentrated sorbitol is broadly used for general industrial use because its price is extremely cheaper than that of the powdered sorbitol. The concentrated sorbitol, however, cannot be used in some areas such as pharmaceuticals, cosmetics, or food restricted in the use of water, or in such a cold place that the concentrated sorbitol becomes too viscous to be weighed or is frozen or crystallized. In such areas powdered sorbitol may be conveniently used because it does not contain water or easy to weigh (possible use of a general automatic weigher). Sorbitol powder obtained by simply drying a concentrated sorbitol solution and powdering it has a tendency to form a mass or a cake with time even if it is stored under dry condition, becomes difficult to be dealt, and loses the commercial validity in its appearance.
Accordingly, methods of production of sorbitol powder which hardly forms cakes, or methods of preventing the sorbitol powder from caking have been proposed.
In one of the simplest methods of production of non-caking sorbitol powder, crystalline sorbitol (seed) is added to melted dried sorbitol, and then gradually cooled to 30.degree. C. or lower over long time, for instance, over about 24 hours to give powder. This process needs too long time to be applied to an industrial use.
As a method to improve the above process there is proposed in Japanese Patent Publication No. 36206/1974 that a concentrated aqueous solution of sorbitol is continuously supplied with seeds into a specific mixer, mixed, discharged, and then held at room temperature. In this method a long cooling time is also necessary to obtain a sorbitol powder having no tendency of caking.
As another method of preventing the sorbitol powder from caking it is proposed in Japanese Patent Application KOKAI No. 133229/1981 that a sorbitol powder is mixed at a temperature of 50.degree. C. or more but lower than the melting point. The principle of this method is to change the surface condition of sorbitol powder. A problem of this method is that the sorbitol once powdered is necessarily treated again.